Just following up here. Very excited to say I got my old system working! 
It has been producing solidly for about 3 weeks now. It was so much easier than I had expected. The story goes like this:
I received a replacement SJ-20 cell. I installed it and turned it on. It didn't work..started blinking with error after a bit. I figured out it was because my salt level was under 3500, so it wasn't going to work until I got more salt since my level was about 2000 --we had so much rain lately and did a lot of draining. I didn't have any bags of salt on hand.
FLASH BACK--as mentioned, the rating of my old in-deck cell is to have input power of "3.0 Amps @ 10 – 16 VDC". In the spec, also it only required 2500 salt. A few days before that, I thought I'd try a Hail Mary and just buy a converter that took AC and outputted DC 12v at about 3 amps. I found a waterproof 12v 40w power supply on amazon for $18 (https://www.amazon.com/gp/product/B07VBLKHF9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1), so I ordered it [NOTE: weirdly the 40 watt version is not available anymore on that one, it's 30 or 60 watts now]. It arrived on the same day as I got my replacement SJ-20. When the SJ-20 didn't work (due to low salt) I temporarily wired it together the old cell, and it started producing even at 2000 ppm salt!
I knew this was a direction I wanted to keep exploring, but I needed a way to turn it on/off on a schedule. I ordered a smart plug (VAVOFO Outdoor Smart Plug, WiFi Outlet with 2 Sockets, Compatible with Alexa Google Home, IP44 Waterproof, Wireless Remote Control Timer & Countdown by Smartphone APP - - Amazon.com) and some banana clips (Amazon.com: Aodesy Dual Copper 4mm 2-Way Banana Plug Jack Socket Binding Post for Speaker Amplifier Terminal,Pack of 4: Industrial & Scientific). Stuff here: New video by Bailey Marie. I got it all setup, and for a total cost of about $50. In other words, I finally found a way to replace my old Auto Pilot Cubby controller with ancient circuitry looked like this: New photo by Bailey Marie
Here is the system working: New video by Bailey Marie
The last task I need to handle is that the old controller would auto-reverse the polarity in an effort to 'auto-clean' the cell. I need to think of some way to auto-reverse polarity perhaps every other day. At present, I am just manually reversing the banana plugs every few days. Will follow up if I think of an auto-solution there.
I know my situation is oddball, but it might be an interesting DIY salt cell system to consider. A cell that produces chlorine directly in the pool vs within the plumbing has advantages. After getting the in-deck solution going, I was able to reduce my pump runtime back to 4 hrs from 8hrs (that's a huge power savings!). I do still run the cell power for 10 hrs using the WIFI power controller schedule. That has kept my FC levels solid (2019-11-16_20-40-50.png). Also, I do not know what the power consumption was for the SJ-20 (could not find it), but based just on the massive size of the controller, it just seems like it had to be sucking a lot more power over 8 hrs than this tiny 40 watt strip over 10 hrs.
Feeling Adventurous? Here is how to do what I did:
First, buy this cell: https://www.poolsupplyunlimited.com/pool/autopilot-400-5-cubby-salt-cell-replacement/56678p1. Then find a way to float it or in-deck install it (see page 8 of the attached Old Cubby Manual). Then power it with the $50 solution above. You'll have a really clever, efficient low salt-system thats probably good for up to 15-20k gallons for under $550.
Consideration: I am concerned that the cell linked might no longer be available after some time since it is considered obsolete. I plan to get rid of my SJ-20 (maybe return or sell it) and then maybe buy a couple backup cells to make my solution future-proof for at least the next 6-8 years.
It has been producing solidly for about 3 weeks now. It was so much easier than I had expected. The story goes like this:I received a replacement SJ-20 cell. I installed it and turned it on. It didn't work..started blinking with error after a bit. I figured out it was because my salt level was under 3500, so it wasn't going to work until I got more salt since my level was about 2000 --we had so much rain lately and did a lot of draining. I didn't have any bags of salt on hand.
FLASH BACK--as mentioned, the rating of my old in-deck cell is to have input power of "3.0 Amps @ 10 – 16 VDC". In the spec, also it only required 2500 salt. A few days before that, I thought I'd try a Hail Mary and just buy a converter that took AC and outputted DC 12v at about 3 amps. I found a waterproof 12v 40w power supply on amazon for $18 (https://www.amazon.com/gp/product/B07VBLKHF9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1), so I ordered it [NOTE: weirdly the 40 watt version is not available anymore on that one, it's 30 or 60 watts now]. It arrived on the same day as I got my replacement SJ-20. When the SJ-20 didn't work (due to low salt) I temporarily wired it together the old cell, and it started producing even at 2000 ppm salt!
I knew this was a direction I wanted to keep exploring, but I needed a way to turn it on/off on a schedule. I ordered a smart plug (VAVOFO Outdoor Smart Plug, WiFi Outlet with 2 Sockets, Compatible with Alexa Google Home, IP44 Waterproof, Wireless Remote Control Timer & Countdown by Smartphone APP - - Amazon.com) and some banana clips (Amazon.com: Aodesy Dual Copper 4mm 2-Way Banana Plug Jack Socket Binding Post for Speaker Amplifier Terminal,Pack of 4: Industrial & Scientific). Stuff here: New video by Bailey Marie. I got it all setup, and for a total cost of about $50. In other words, I finally found a way to replace my old Auto Pilot Cubby controller with ancient circuitry looked like this: New photo by Bailey Marie
Here is the system working: New video by Bailey Marie
The last task I need to handle is that the old controller would auto-reverse the polarity in an effort to 'auto-clean' the cell. I need to think of some way to auto-reverse polarity perhaps every other day. At present, I am just manually reversing the banana plugs every few days. Will follow up if I think of an auto-solution there.
I know my situation is oddball, but it might be an interesting DIY salt cell system to consider. A cell that produces chlorine directly in the pool vs within the plumbing has advantages. After getting the in-deck solution going, I was able to reduce my pump runtime back to 4 hrs from 8hrs (that's a huge power savings!). I do still run the cell power for 10 hrs using the WIFI power controller schedule. That has kept my FC levels solid (2019-11-16_20-40-50.png). Also, I do not know what the power consumption was for the SJ-20 (could not find it), but based just on the massive size of the controller, it just seems like it had to be sucking a lot more power over 8 hrs than this tiny 40 watt strip over 10 hrs.
Feeling Adventurous? Here is how to do what I did:
First, buy this cell: https://www.poolsupplyunlimited.com/pool/autopilot-400-5-cubby-salt-cell-replacement/56678p1. Then find a way to float it or in-deck install it (see page 8 of the attached Old Cubby Manual). Then power it with the $50 solution above. You'll have a really clever, efficient low salt-system thats probably good for up to 15-20k gallons for under $550.
Consideration: I am concerned that the cell linked might no longer be available after some time since it is considered obsolete. I plan to get rid of my SJ-20 (maybe return or sell it) and then maybe buy a couple backup cells to make my solution future-proof for at least the next 6-8 years.